Magnetic Circular Dichroism (MCD), Ultraviolet (UV) and Fluorescence Spectroscopy (FS) will be used to investigate the spectroscopic effects of chemical substitution of the indole system with the intent of interpreting the MCD spectra. A red-shift of the first absorption band upon 5-hydroxy substitution will be exploited using MCD time-averaged spectra to monitor the enzymatic hydroxylation of 1-tryptophan in vitro. These studies are intended to elucidate the biosynthesis of serotonin.